JP2010177586A - Light-emitting element and method for manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a light-emitting element capable of improving heat radiation performance and further improving light extracting efficiency by forming unevenness on the surface of a transparent conductor layer near a light emitter and controlling its interval pitch and shape: and to provide a method for manufacturing the light-emitting element. <P>SOLUTION: The light-emitting element comprises at least a transparent conductive layer having a refractive index of not less than 1.7. The surface of the transparent conductive layer has a recessed and projected part which is formed by providing the surface of the transparent conductive layer with a plurality of portions that are recessed with respect to the surface taken as the reference. The shortest distance between the centers of adjacent recessed portions is not less than 100 nm but not more than 1,200 nm, and the depth of each recessed portion is not less than 60 nm but not more than 350 nm. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a light emitting element such as an LED (Light Emitting Diode) with improved light extraction efficiency and a method for manufacturing the light emitting element.

Light-emitting elements such as LEDs, fluorescent lamps, EL elements, and plasma displays have a light-emitting body exterior member formed of a transparent lens, a protective film, or a glass tube, and light is emitted from the surface (light-emitting surface) of these exterior members. Is released to the outside.
The refractive index of such a transparent exterior member is generally much larger than the refractive index of air, and reflection occurs at the interface when light is about to exit from the exterior member. Depending on the angle, the reflected light cannot go out from the exterior member, and eventually becomes heat. In addition, inorganic semiconductor materials such as GaN and GaAs are used for the light emitters of LEDs, but these materials have a high refractive index and are internally reflected at the interface with the outside where the refractive index is low, leading to the outside. It is difficult to extract light.

As means for solving such a decrease in luminous efficiency, a technique of providing a fine uneven structure on the surface of the light emitting surface is disclosed (see Patent Documents 1 and 2).
However, when the unevenness processing is performed on the light emitting body itself, there is a problem that distortion or the like occurs in the light emitting body in the processing process and the light emission amount itself decreases. In addition, when unevenness is formed on the exterior member away from the light emitter, there is a problem that multiple reflections occur inside the exterior member and the amount of light decreases due to material absorption, and further improvement and development are desired. Is the current situation.

JP 2003-174191 A JP 2007-109946 A

  An object of the present invention is to solve the above-described problems and achieve the following objects. That is, the present invention provides a light emitting device capable of improving heat dissipation and further improving light extraction efficiency by forming irregularities on the surface of the transparent conductor layer in the vicinity of the light emitter and controlling the interval pitch and shape thereof. It is an object of the present invention to provide a method for manufacturing the light emitting element.

Means for solving the problems are as follows. That is,
<1> A light emitting device having at least a transparent conductor layer having a refractive index of 1.7 or more,
The surface of the transparent conductor layer has an uneven portion formed by arranging a plurality of recesses on the basis of the surface,
The light-emitting element is characterized in that the shortest distance between the centers of adjacent recesses is 100 nm to 1,200 nm and the recess depth is 60 nm to 350 nm.
<2> The light emitting device according to <1>, wherein the shortest distance between the centers of adjacent recesses is 250 nm to 800 nm and the recess depth is 150 nm to 250 nm.
<3> The light-emitting element according to any one of <1> to <2>, including a substrate, at least one inorganic semiconductor layer on the substrate, and a transparent conductor layer in this order.
<4> A method for producing the light-emitting device according to any one of <1> to <3>,
Forming an organic layer capable of changing the shape of the heat mode on the surface of the transparent conductor layer of the light emitting device, and forming a plurality of holes by irradiating the condensed light on the organic layer; and
A recess forming step of forming a recess corresponding to the hole by performing etching using the organic layer in which the hole is formed as a mask,
It is a manufacturing method of the light emitting element characterized by including.

  According to the present invention, conventional problems can be solved, and irregularities are formed on the surface of the transparent conductor layer in the vicinity of the light emitter, and the spacing pitch and shape are controlled, thereby improving heat dissipation and light extraction efficiency. The light emitting element which can aim at the further improvement of this, and the manufacturing method of this light emitting element can be provided.

FIG. 1 is a schematic cross-sectional view showing an example of a light emitting device of the present invention. FIG. 2A is a diagram illustrating an example of a plan view of the surface of the organic layer. FIG. 2B is a diagram illustrating another example of the surface of the organic layer viewed in a plane. FIG. 3 is a diagram showing a layer structure of the light emitting element used in the simulation in the example.

(Light emitting element)
The light-emitting element of the present invention has at least a transparent conductor layer having a refractive index of 1.7 or more, and includes a substrate, an inorganic semiconductor layer, and other layers as necessary.
The light-emitting element preferably has a substrate, at least one inorganic semiconductor layer on the substrate, and a transparent conductor layer in this order.

In this invention, it has the uneven | corrugated | grooved part formed when the several recessed part was arranged on the said transparent conductor layer surface on the basis of this surface.
Here, as shown in FIG. 1, a plurality of convex portions 105 and concave portions 106 are formed at a constant pitch P on the surface of the transparent conductor layer 101. In this case, the convex portion 105 and the concave portion 106 are collectively referred to as an uneven portion.
The cross-sectional shape of the uneven portion is not limited to a linear shape, and may be curved.

The shortest distance (pitch) between the centers of adjacent recesses is 100 nm or more and 1,200 nm or less, and preferably 250 μm to 800 μm. If the pitch is less than 100 nm, it is considerably smaller than the wavelength of light, so that diffraction / scattering does not occur and the effect of improving the extraction efficiency may be reduced. If the pitch exceeds 1,200 nm, the diffraction angle is considerably larger than the wavelength. Since it is small, the light extraction efficiency improvement effect may be small.
The pitch can be measured by, for example, an atomic force microscope (AFM), a scanning electron microscope (SEM), or the like.

The depth of the recess is 60 nm or more and 350 nm or less, and preferably 150 nm to 250 nm. If the depth of the recess is less than 60 nm, the optical path length difference between the recess and its surroundings is significantly smaller than the wavelength, diffraction and scattering are less likely to occur, and the light extraction effect may be reduced. Formation may be difficult.
The depth of the recess can be measured by, for example, an atomic force microscope (AFM).

-Transparent conductor layer-
There is no restriction | limiting in particular as a material of the said transparent conductor layer, Although it can select suitably according to the objective, For example, electroconductive compounds, such as a metal and a metal oxide, these mixtures etc. are mentioned.
Examples of the material of the transparent conductor layer include conductive metal oxides such as tin oxide, zinc oxide, indium oxide, and indium tin oxide (ITO); metals such as gold, silver, chromium, and nickel; conductive with these metals Inorganic conductive materials such as mixtures or laminates with conductive metal oxides, copper iodide, copper sulfide, etc .; organic conductive materials such as polyaniline, polythiophene, and polypyrrole; and laminates of these with ITO. These may be used individually by 1 type and may use 2 or more types together. Among these, a conductive metal oxide is preferable, and ITO is particularly preferable from the viewpoints of productivity, conductivity, transparency, and the like.

The refractive index of the transparent conductor layer is 1.7 or more, preferably 1.75 to 4, and more preferably 1.8 to 3. If the refractive index is less than 1.7, the difference in refractive index from the light emitter is large, the total reflection amount from the light emitter to the transparent conductor layer interface is large, and light is propagated to the transparent conductor layer. As a result, the light extraction effect in the transparent conductor layer may be reduced.
The refractive index of the transparent conductor layer can be measured, for example, with an ellipsometer.
There is no restriction | limiting in particular as thickness of the said transparent conductor layer, Although it can select suitably with materials etc., from a viewpoint of the balance of an electrical resistance and light absorption, 1 nm-5,000 nm are preferable, and 20 nm-200 nm are preferable. More preferred.

  The transparent conductor layer may be formed by, for example, a vapor deposition method, a wet film forming method, an electron beam method, a sputtering method, a reactive sputtering method, an MBE (molecular beam epitaxy) method, a cluster ion beam method, an ion plating method, a plasma polymerization method. (High frequency excitation ion plating method), molecular lamination method, LB method, printing method, transfer method, method of applying the ITO dispersion by chemical reaction method (sol-gel method, etc.), etc. Can do.

-Board-
The substrate is not particularly limited as to the material, shape, structure, size, etc., and can be appropriately selected according to the purpose. Examples of the material include inorganic materials, organic materials, and the like. As the structure, a single layer structure or a laminated structure may be used as the structure, and the size may be appropriately selected according to the use or the like.
Examples of the inorganic material include glass, sapphire, silicon (Si), and quartz (SiO ₂ ).
Examples of the resin include polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polycarbonate (PC), low-melting fluororesin, polymethyl methacrylate (PMMA), triacetate cellulose (TAC), and the like.

The substrate may be appropriately synthesized or a commercially available product may be used.
There is no restriction | limiting in particular as thickness of the said board | substrate, According to the objective, it can select suitably, 100 micrometers or more are preferable and 500 micrometers or more are more preferable.

-Inorganic semiconductor layer-
The inorganic semiconductor layer is preferably composed of at least one layer and is composed of two or more layers.
As the material of the inorganic semiconductor layer, a semiconductor material having a pn junction or a pin junction such as GaAs, AlGaAs, InP, InGaAsP, ZnS, ZnSe, or CdTe can be used.
A compound semiconductor lattice-matched to each substrate such as GaAs, AlGaAs, InP, or InGaAsP on a single crystal substrate such as GaAs or InP is subjected to an LPE (liquid phase epitaxy) method, an MOCVD (metal organic chemical vapor deposition) method, or a VPE (vapor pore phase). ) Method, MBE (molecular beam epitaxy) method or the like, and epitaxial growth using a crystal growth method such as a method can be performed.
The total thickness of the inorganic semiconductor layer is preferably 100 nm to 10,000 nm.

-Protective layer-
In the present invention, the entire light emitting element may be protected by a protective layer.
As a material contained in the protective layer, any material may be used as long as it has a function of preventing a material that promotes device deterioration such as moisture or oxygen from entering the device.
Examples of the protective layer material include metals such as In, Sn, Pb, Au, Cu, Ag, Al, Ti, and Ni; MgO, SiO, SiO ₂ , Al ₂ O ₃ , GeO, NiO, CaO, BaO, and Fe Metal oxides such as ₂ O ₃ , Y ₂ O ₃ and TiO ₂ ; Metal nitrides such as SiN _x and SiN _x O _y ; Metal fluorides such as MgF ₂ , LiF, AlF ₃ and CaF ₂ ; Polyethylene, polypropylene, Contains polymethyl methacrylate, polyimide, polyurea, polytetrafluoroethylene, polychlorotrifluoroethylene, polydichlorodifluoroethylene, a copolymer of chlorotrifluoroethylene and dichlorodifluoroethylene, tetrafluoroethylene and at least one comonomer Copolymer obtained by copolymerizing monomer mixture, copolymerization Examples thereof include a fluorine-containing copolymer having a cyclic structure in the main chain, a water-absorbing substance having a water absorption of 1% or more, and a moisture-proof substance having a water absorption of 0.1% or less.

  The method for forming the protective layer is not particularly limited. For example, the vacuum deposition method, the sputtering method, the reactive sputtering method, the MBE (molecular beam epitaxy) method, the cluster ion beam method, the ion plating method, the plasma polymerization method ( High frequency excitation ion plating method), plasma CVD method, laser CVD method, thermal CVD method, gas source CVD method, coating method, printing method, transfer method can be applied.

  The light emitting device of the present invention is suitably used for, for example, an LED, a fluorescent lamp, an EL (electro luminescence) device, a plasma display, etc. Among them, an LED is particularly preferable.

(Manufacturing method of light emitting element)
The manufacturing method of the light emitting element of this invention is a method of manufacturing the said light emitting element of this invention, Comprising: A hole part formation process and a recessed part formation process are included, and also the other process is included as needed.

<Hole formation process>
The hole forming step is a step of forming an organic layer capable of changing the heat mode shape on the surface of the transparent conductor layer of the light emitting element, and forming a plurality of holes by irradiating the condensed light on the organic layer. It is.

The organic layer capable of changing the shape of the heat mode is a layer in which light is converted into heat by irradiation of intense light, and the shape of the material can be changed by this heat to form a recess. Phthalocyanine, quinone, squarylium, azulenium, thiol complex, merocyanine, and the like can be used.
Suitable examples include methine dyes (cyanine dyes, hemicyanine dyes, styryl dyes, oxonol dyes, merocyanine dyes, etc.), macrocyclic dyes (phthalocyanine dyes, naphthalocyanine dyes, porphyrin dyes, etc.), azo dyes (azo metal chelate dyes, etc.) ), Arylidene dyes, complex dyes, coumarin dyes, azole derivatives, triazine derivatives, 1-aminobutadiene derivatives, cinnamic acid derivatives, quinophthalone dyes, and the like. Among these, methine dyes and azo dyes are particularly preferable.

In addition, the organic layer can select a pigment | dye suitably according to the wavelength of a laser light source, or can modify | change a structure.
For example, when the oscillation wavelength of the laser light source is around 780 nm, it is advantageous to select from pentamethine cyanine dye, heptamethine oxonol dye, pentamethine oxonol dye, phthalocyanine dye, naphthalocyanine dye, and the like.
When the oscillation wavelength of the laser light source is around 660 nm, it is advantageous to select from trimethine cyanine dye, pentamethine oxonol dye, azo dye, azo metal complex dye, pyromethene complex dye, and the like.
Further, when the oscillation wavelength of the laser light source is around 405 nm, monomethine cyanine dye, monomethine oxonol dye, zero methine merocyanine dye, phthalocyanine dye, azo dye, azo metal complex dye, porphyrin dye, arylidene dye, complex It is advantageous to select from dyes, coumarin dyes, azole derivatives, triazine derivatives, benzotriazole derivatives, 1-aminobutadiene derivatives, quinophthalone dyes, and the like.

  In the following, examples of compounds preferable as the organic layer are given in the case where the oscillation wavelength of the laser light source is around 405 nm. The compounds represented by the following III-1 to III-14 are compounds when the oscillation wavelength of the laser light source is around 405 nm. In addition, when the oscillation wavelength of the laser light source is around 780 nm, preferred compounds in the case of around 660 nm include the compounds described in paragraphs [0024] to [0028] of JP-A-2008-252056. It is done. In addition, this invention is not limited to the case where these compounds are used.

<Example of compound when the oscillation wavelength of the laser light source is around 405 nm>

<Example of compound when the oscillation wavelength of the laser light source is around 405 nm>

  JP-A-4-74690, JP-A-8-127174, 11-53758, 11-334204, 11-334205, 11-334206, 11-334207 The dyes described in JP-A No. 2000-43423, JP-A No. 2000-108513, JP-A No. 2000-158818, and the like are also preferably used.

For such a dye-type organic layer, a dye is dissolved in an appropriate solvent together with a binder and the like to prepare a coating solution, and then this coating solution is applied to the surface of the transparent conductor layer to form a coating film. Then, it can be formed by drying. In that case, it is preferable that the temperature of the surface which apply | coats a coating liquid is the range of 10-40 degreeC. The lower limit is more preferably 15 ° C. or higher, further preferably 20 ° C. or higher, and particularly preferably 23 ° C. or higher. Moreover, as an upper limit, it is more preferable that it is 35 degrees C or less, It is still more preferable that it is 30 degrees C or less, It is especially preferable that it is 27 degrees C or less. Thus, when the coated surface temperature is within the above range, it is possible to prevent the occurrence of coating unevenness and coating failure and to make the thickness of the coating film uniform. Each of the upper limit value and the lower limit value can be arbitrarily combined.
Here, the organic layer may be a single layer or a multilayer. In the case of a multilayer structure, the organic layer is formed by performing the coating process a plurality of times.
The concentration of the dye in the coating solution is preferably 0.3% by mass or more and 30% by mass or less, more preferably 1% by mass or more and 20% by mass or less, more preferably tetrafluoropropanol. It is particularly preferable to dissolve in 1 mass% or more and 20 mass% or less.

There is no restriction | limiting in particular as a solvent of a coating liquid, According to the objective, it can select suitably, For example, Esters, such as butyl acetate, ethyl lactate, and cellosolve acetate; Ketones, such as methyl ethyl ketone, cyclohexanone, and methyl isobutyl ketone; Dichloromethane, 1 Chlorinated hydrocarbons such as 1,2-dichloroethane and chloroform; Amides such as dimethylformamide; Hydrocarbons such as methylcyclohexane; Ethers such as tetrahydrofuran, ethyl ether and dioxane; Ethanol, n-propanol, isopropanol, n-butanol diacetone alcohol Alcohols such as: Fluorine solvents such as 2,2,3,3-tetrafluoropropanol; Ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, propylene glycol mono Glycol ethers such as Chirueteru; and the like. Among these, butyl acetate, ethyl lactate, cellosolve acetate, methyl ethyl ketone, isopropanol, and 2,2,3,3-tetrafluoropropanol are particularly preferable.
The above solvents can be used alone or in combination of two or more in consideration of the solubility of the dye used. In the coating solution, various additives such as an antioxidant, a UV absorber, a plasticizer, and a lubricant may be added according to the purpose.

Examples of the coating method include a spray method, a spin coating method, a dip method, a roll coating method, a blade coating method, a doctor roll method, a doctor blade method, and a screen printing method. In addition, it is preferable to employ the spin coating method in terms of excellent productivity and easy control of the film thickness.
The organic layer is preferably dissolved in an amount of 0.3% by mass or more and 30% by mass or less, and preferably 1% by mass or more and 20% by mass or less, with respect to the organic solvent, because it is advantageous for formation by spin coating. It is more preferable.
Further, the dye preferably has a thermal decomposition temperature of 150 ° C. or higher and 500 ° C. or lower, and more preferably 200 ° C. or higher and 400 ° C. or lower.
During coating, the temperature of the coating solution is preferably 23 ° C to 50 ° C, more preferably 24 ° C to 40 ° C, and further preferably 25 ° C to 30 ° C.

When the coating solution contains a binder, the binder is not particularly limited and may be appropriately selected depending on the intended purpose. For example, natural organic polymer substances such as gelatin, cellulose derivatives, dextran, rosin, and rubber; Hydrocarbon resins such as polyethylene, polypropylene, polystyrene, polyisobutylene, vinyl resins such as polyvinyl chloride, polyvinylidene chloride, polyvinyl chloride / polyvinyl acetate copolymer, polymethyl acrylate, polymethyl methacrylate, etc. And synthetic organic polymers such as acrylic resins, polyvinyl alcohol, chlorinated polyethylene, epoxy resins, butyral resins, rubber derivatives, and initial condensates of thermosetting resins such as phenol / formaldehyde resins.
When a binder is used in combination as the material for the organic layer, the amount of the binder used is generally preferably 0.01 to 50 times (mass ratio) with respect to the dye, and 0.1 to 5 times. The amount (mass ratio) is more preferable.

The organic layer can contain various anti-fading agents in order to improve the light resistance of the organic layer.
As the antifading agent, a singlet oxygen quencher is generally used. As the singlet oxygen quencher, those described in publications such as known patent specifications can be used.
Specific examples thereof include JP-A Nos. 58-175893, 59-81194, 60-18387, 60-19586, 60-19587, and 60-35054. 60-36190, 60-36191, 60-44554, 60-44555, 60-44389, 60-44390, 60-54892, JP-A-60-47069, JP-A-63-209995, JP-A-4-25492, JP-B-1-38680, JP-A-6-26028, etc., German Patent No. 350399, Journal of the Chemical Society of Japan Examples include those described in the October 1992 issue, page 1141 and the like.
The amount of the anti-fading agent such as the singlet oxygen quencher used is preferably in the range of 0.1% by mass to 50% by mass and more preferably in the range of 0.5% by mass to 45% by mass with respect to the amount of the dye. The range of 3% by mass to 40% by mass is more preferable, and the range of 5% by mass to 25% by mass is particularly preferable.

  Although the organic layer solvent coating method has been described above, the organic layer can also be formed by a film forming method such as vapor deposition, sputtering, or CVD.

In addition, the pigment | dye has a higher light absorptivity in the wavelength of the laser beam used for the process of the hole part mentioned later than other wavelengths.
The wavelength of the absorption peak of the dye is not necessarily limited to that in the visible light wavelength range, and may be in the ultraviolet range or the infrared range.

The wavelength λw for forming the hole with the laser is preferably in a relationship of λa <λw. In such a relationship, the light absorption amount of the dye is appropriate, the recording efficiency is increased, and a clean uneven shape may be formed in some cases. Further, it is preferable that λw <λc. Since λw should be the wavelength that the dye absorbs, the light emitted from the light-emitting element is not absorbed by the dye and the transmittance is improved by having the center wavelength λc of the light-emitting element on the longer wavelength side than the wavelength of λw. As a result, the luminous efficiency can be improved.
From the above viewpoint, it can be said that the relationship of λa <λw <λc is most preferable.

  Note that the wavelength λw of the laser light for forming the hole may be a wavelength that provides a large laser power. For example, when a dye is used for the organic layer, 193 nm, 210 nm, 266 nm, 365 nm, 405 nm, 488 nm 1,000 nm or less is preferable, such as 532 nm, 633 nm, 650 nm, 680 nm, 780 nm, and 830 nm.

  The laser beam may be any laser such as a gas laser, a solid laser, or a semiconductor laser. However, in order to simplify the optical system, it is preferable to employ a solid laser or a semiconductor laser. The laser light may be continuous light or pulsed light, but it is preferable to employ laser light whose emission interval can be freely changed. For example, it is preferable to employ a semiconductor laser. When the laser cannot be directly on / off modulated, it is preferable to modulate with an external modulation element.

  Further, the laser power is preferably higher in order to increase the processing speed. However, as the laser power is increased, the scanning speed (speed at which the organic layer is scanned with laser light) must be increased. Therefore, the upper limit value of the laser power is preferably 100 W in consideration of the upper limit value of the scanning speed, more preferably 10 W, still more preferably 5 W, and particularly preferably 1 W. The lower limit of the laser power is preferably 0.1 mW, more preferably 0.5 mW, and even more preferably 1 mW.

  Further, the laser light is preferably light that has excellent transmission wavelength width and coherency, and can be narrowed down to a spot size equivalent to the wavelength. Further, it is preferable to adopt a strategy such as that used in an optical disk as the light pulse irradiation condition for properly forming the hole. That is, it is preferable to adopt conditions such as recording speed, the peak value of the irradiated laser beam, and the pulse width as used in an optical disc.

The thickness of the organic layer should correspond to the depth of the hole 15 described later.
This thickness can be appropriately set within a range of 1 nm to 10,000 nm, for example, and the lower limit of the thickness is preferably 10 nm or more, and more preferably 30 nm or more. If the thickness is too small, the hole portion 15 is formed shallow, so that an optical effect may not be obtained. Further, the upper limit of the thickness is preferably 1,000 nm or less, and more preferably 500 nm or less. If the thickness is too thick, a large laser power is required, and it may be difficult to form a deep hole, and the processing speed may be reduced.

  Moreover, it is preferable that the thickness t of the organic layer and the diameter d of the hole have the following relationship. That is, the upper limit value of the thickness t of the organic layer is preferably a value satisfying t <10d, more preferably a value satisfying t <5d, and a value satisfying t <3d. preferable. The lower limit value of the thickness t of the organic layer is preferably a value satisfying t> d / 100, more preferably a value satisfying t> d / 10, and a value satisfying t> d / 5. Is more preferable. The reason why the upper limit value and the lower limit value of the thickness t of the organic layer are set in relation to the diameter d of the hole is the same as described above.

  When forming the organic layer, after preparing a coating solution by dissolving or dispersing the dye in an appropriate solvent, the surface of the transparent conductor layer is applied by a coating method such as spin coating, dip coating or extrusion coating. It can form by apply | coating to.

  A plurality of holes are periodically formed in the organic layer. The hole portion is formed by irradiating the condensed light on the organic layer to deform the irradiated portion (including deformation due to disappearance).

The principle of forming the hole is as follows.
When the organic layer is irradiated with laser light having a wavelength at which the material absorbs light (wavelength absorbed by the material), the organic layer absorbs the laser light, and the absorbed light is converted into heat, which is irradiated with light. The temperature of the part rises. As a result, the organic layer undergoes chemical or / and physical changes such as softening, liquefaction, vaporization, sublimation, and decomposition. And the hole part is formed because the material which caused such a change moves or / and disappears.

  As the hole forming method, for example, a pit forming method known for a write-once optical disc or a write-once optical disc can be applied. Specifically, for example, by detecting the intensity of the reflected light of the laser that changes depending on the pit size, and correcting the output of the laser so that the intensity of the reflected light is constant, a uniform pit is formed. A known running OPC technique (Japanese Patent No. 3096239) can be applied.

  Further, the vaporization, sublimation or decomposition of the organic layer as described above preferably has a large rate of change and is steep. Specifically, the mass reduction rate by differential thermal balance (TG-DTA) at the time of vaporization, sublimation or decomposition of the dye is preferably 5% or more, more preferably 10% or more, and further preferably 20% or more. . Further, the slope of mass decrease by differential thermal balance (TG-DTA) at the time of vaporization, sublimation or decomposition of the pigment (the mass decrease rate per 1 ° C. temperature rise is preferably 0.1% / ° C. or more, and 2% / ° C or more is more preferable, and 0.4% / ° C or more is more preferable.

  Further, the transition temperature of chemical or / and physical change such as softening, liquefaction, vaporization, sublimation, and decomposition has an upper limit of preferably 2,000 ° C. or lower, more preferably 1,000 ° C. or lower. Preferably, it is 500 degrees C or less. If the transition temperature is too high, a large laser power may be required. Further, the lower limit of the transition temperature is preferably 50 ° C. or higher, more preferably 100 ° C. or higher, and further preferably 150 ° C. or higher. If the transition temperature is too low, the temperature gradient with respect to the surroundings is small, and it may be impossible to form a clear hole edge shape.

  FIG. 2A is a diagram of an example in which the organic layer is viewed in plan, and FIG. 2B is a diagram of another example in which the organic layer is viewed in plan. As shown in FIG. 2A, the holes 15 may be formed in a dot shape, and the dots arranged in a lattice shape. Moreover, as shown in FIG. 2B, the hole 15 may be formed in an elongated groove shape, and this may be intermittently connected. Further, although not shown, it can be formed as a continuous groove shape.

  The pitch P between the adjacent hole portions 15 is 0.01 to 100 times the center wavelength λc of the light emitted by the LED element 10 that is a light emitter.

  The pitch P of the holes 15 is preferably 0.05 to 20 times the center wavelength λc, more preferably 0.1 to 5 times, and still more preferably 0.5 to 2 times. Specifically, the lower limit of the pitch P is preferably 0.01 times or more of the center wavelength λc, more preferably 0.05 times or more, still more preferably 0.1 times or more, and particularly preferably 0.2 times or more. . The upper limit value of the pitch P is preferably 100 times or less, more preferably 50 times or less, still more preferably 10 times or less, and particularly preferably 5 times or less the center wavelength λc.

The diameter of the hole 15 or the width of the groove is preferably 0.005 to 25 times the center wavelength λc, more preferably 0.025 to 10 times, still more preferably 0.05 to 2.5 times, and 0.25 to 0.25 Two times is particularly preferred.
The diameter or the width of the groove here is a size at a half depth of the hole portion 15, a so-called half width.

  The diameter of the hole 15 or the width of the groove can be appropriately set within the above range, but depending on the size of the pitch P so that the refractive index gradually decreases macroscopically as the distance from the light emitting surface 18 increases. It is preferable to adjust. That is, when the pitch P is large, the diameter of the hole 15 or the width of the groove is also increased. When the pitch P is small, the diameter of the hole 15 or the width of the groove is preferably decreased. From this viewpoint, the diameter or the width of the groove is preferably about a half of the pitch P. For example, 20% to 80% of the pitch P is preferable, and 30% to 70% is more preferable. Preferably, 40% to 60% is more preferable.

  The depth of the hole 15 is preferably 0.01 to 20 times the center wavelength λc, more preferably 0.05 to 10 times, still more preferably 0.1 to 5 times, and particularly preferably 0.2 to 2 times. .

-Recess formation process-
The recess forming step is a step of forming a recess corresponding to the hole by performing etching using the organic layer in which the hole is formed as a mask.

The etching is not particularly limited, and various etching methods such as wet etching and dry etching can be used. However, reactive ion etching (RIE), which has high etching gas straightness and enables fine patterning, is used. Is preferred.
In the case where the organic layer is easily scraped by the etching gas, an etching mask layer may be formed on the transparent conductor layer surface.
Moreover, as a removal method of an organic layer and / or an etching mask layer, a dry method, a wet method, etc. are employable, for example.

  Examples of other processes include a protective layer forming process and an etching mask layer forming process.

  According to the method for manufacturing a light emitting element of the present invention, a controlled recess can be efficiently formed in a simple process on the surface of the transparent conductor layer in the vicinity of the light emitter of the light emitting element.

  Examples of the present invention will be described below, but the present invention is not limited to these examples.

(Examples 1-6 and Comparative Examples 1-9)
-Fabrication of light-emitting elements (simulation)-
As shown in FIG. 3, a sapphire substrate (refractive index (n) = 1.9, k = 0, thickness 200 nm) 103 and an inorganic semiconductor layer (refractive index (n) = 2.4, k = 0, thickness) 500 nm) 102 and a transparent conductive layer (refractive index (n) = 1.9, k = 0, thickness 100 nm) 101, relative evaluation of light emission amount is performed by simulation as follows. went.
The uneven interface is provided on the transparent conductor layer surface P, the semiconductor layer surface Q, the semiconductor layer back surface R, or the sapphire substrate back surface S, and the light emission position 104 is in the thickness direction from the interface between the sapphire substrate 103 and the inorganic semiconductor layer 102. The depth D was in the inorganic semiconductor layer having a thickness of 100 nm. The emission wavelength was 460 nm.

<Evaluation method of light emission amount>
Comparison in which the uneven interface is not provided by changing the position, interval pitch, and concave depth of the uneven interface as shown in Table 1 by two-dimensional (2D) FDTD calculation using RSSoft software (FullWave) The relative light emission amount was evaluated with the light emission amount of Example 1 being 1. The results are shown in Table 1.

(Example 7)
-Fabrication of light-emitting elements-
On the sapphire substrate, an inorganic semiconductor layer having a thickness of 4,000 nm mainly composed of GaN was formed by epitaxial growth.
Next, indium tin oxide (ITO) having a thickness of 300 nm was formed as a transparent conductor layer on the inorganic semiconductor layer by sputtering. The refractive index of this transparent conductor layer was 1.9.
Next, Ti having a thickness of 30 nm and SiO ₂ having a thickness of 100 nm were formed by sputtering as an etching mask layer on the transparent conductor layer.
Next, a solution obtained by dissolving 40 mg of an oxonol organic compound represented by the following structural formula in 1 ml of 2,2,3,3-tetrafluoro-1-propanol on the etching mask layer was rotated at 300 rpm using a spin coater. And then dried at 1,000 rpm to form an organic layer having a thickness of 210 nm.

Next, laser irradiation was performed on the organic layer with NEO1000 (manufactured by Pulstec Industrial Co., Ltd.) at 5 m / s, 8 mW, and 0.5 μm pitch in both the circumferential direction and the radial direction.
Next, SiO ₂ is processed by dry etching using CF ₄ as an etching gas, and ITO is further processed by CF ₄ / O ₂ gas to obtain a light-emitting element having a transparent conductor layer in which concave portions are formed. It was.
When the surface of the transparent conductor layer of the manufactured light-emitting element was observed with a scanning electron microscope (SEM), a plurality of recesses having a shortest distance between the centers of adjacent recesses of 300 nm and a recess depth of 100 nm were formed. It had been.

(Comparative Example 10)
-Fabrication of light-emitting elements-
In Example 7, a light emitting device was produced in the same manner as in Example 7 except that the concave portion was not formed on the surface of the transparent conductor layer.

Next, the light emission amount of Example 7 and Comparative Example 10 was measured as follows. The results are shown in Table 2.
<Measurement of light emission>
Measurement was performed by collecting the emitted light by an integrating sphere and guiding it to a power meter. Q8230 manufactured by Advantest Corporation was used as the power meter.

  Since the light emitting device of the present invention forms irregularities on the surface of the transparent conductor layer in the vicinity of the light emitter, and controls the interval pitch and shape, it is possible to improve heat dissipation and further improve the light extraction efficiency. For example, it is suitably used for an LED, a fluorescent lamp, an EL (electroluminescence) element, a plasma display, etc. Among them, the LED is particularly preferable.

DESCRIPTION OF SYMBOLS 12 Organic layer 15 Hole 101 Transparent conductor layer 102 Inorganic semiconductor layer 103 Substrate 104 Light emission position 105 Convex part 106 Concave part

Claims (4)

A light emitting device having at least a transparent conductor layer having a refractive index of 1.7 or more,
The surface of the transparent conductor layer has an uneven portion formed by arranging a plurality of recesses on the basis of the surface,
A light emitting element characterized in that the shortest distance between the centers of adjacent recesses is 100 nm to 1,200 nm and the recess depth is 60 nm to 350 nm.   2. The light emitting device according to claim 1, wherein the shortest distance between the centers of adjacent recesses is 250 nm to 800 nm and the recess depth is 150 nm to 250 nm.   The light emitting element according to claim 1, comprising a substrate, at least one inorganic semiconductor layer on the substrate, and a transparent conductor layer in this order. A method for producing the light-emitting device according to claim 1,
Forming an organic layer capable of changing the shape of the heat mode on the surface of the transparent conductor layer of the light emitting device, and forming a plurality of holes by irradiating the condensed light on the organic layer; and
A recess forming step of forming a recess corresponding to the hole by performing etching using the organic layer in which the hole is formed as a mask,
A method for manufacturing a light emitting element comprising: